The present invention relates generally to electrophotography, more particularly, to a non-contact developing system that utilizes only one image-receiving member that transfers images directly to media.
Electrophotographic imaging process (or xerography) is a well-known method of copying or otherwise printing documents. In general, electrophotographic imaging uses a charge-retentive, photosensitive surface (known as a photoreceptor) that is initially charged uniformly. The photoreceptor is then exposed to a light image representation of a desired image that discharges specific areas of the photoreceptor surface creating an electrostatic latent image. Toner powder is applied by using a developing system, which carries the toner from a toner container to the latent image, forming a developed image. This developed image is then transferred from the photoreceptor to a substrate (e.g. paper, transparency, and the like).
A color electrophotographic imaging process is typically achieved by repeating the same process described above for each color of toner used and storing each developed color toner image to an accumulator until all desired colors are achieved and than transferred to a substrate (e.g. paper, transparency, and the like).
Previous attempts of producing an imaging system without the use of an accumulator have used redundant charging and exposing systems to prepare the developed toner for passing through each developing station (e.g., Yellow, Magenta, Cyan and Black) without being disturbed by the subsequent developing process. More specifically, each developing station requires an exposing and a charging means to enable the developing process to occur before entering the next developing station. Although adequate imaging can be achieved by using this process, the cost and complexity of the machine is significantly increased due to the need of additional exposing and charging means.
The present invention is directed to a non-contact developing system for electrophotographic machines that effectively reduces the cost and complexity of typical color electrophotographic imaging systems at the same time enabling the ability to directly transfer a developed image to a substrate (e.g. paper, transparency, and the like) without the use of an accumulator.
In a particularly innovative aspect, the developing system of the present invention reduces the need for redundant charging and exposing means by preparing the subsequent developing station for a desired condition or response before the first developed toner carried by the photoreceptor passes. More particularly, when subsequent developing is not required the subsequent developing station is prepared for a desired condition by cleaning a toner support member of the developing station of any toner before the first developed toner or latent image passes to ensure contamination of colors or partial development does not occur. The method of preparing the subsequent developing stations for a desired condition enables the first developed image to pass through the subsequent developing station and be carried by the photoreceptor to the next available charging and exposing means. Once the first developed toner and the photoreceptor is prepared for an additional developed toner by the next available charging and exposing means it is returned to a desired developing station where an additional color is developed. This process is repeated until the desired colors are achieved and then transferred to a substrate (e.g. paper, transparency, and the like).